Validation Of Program CENCOM Predictions Against Experimental Data
This is a high flow coefficient industrial compressor stage with a covered full-inducer impeller, vaneless diffuser and a return channel. All predicted and experimental data are normalized by their design point values. Predicted and experimental stage work input coefficients are shown as well as polytropic head coefficents at the impeller, diffuser and return channel (stage) exits. An inducer stall is predicted at the indicated location. This is clearly consistent with the the impeller exit polytropic head coefficient experimental data at nearly the same flow coefficient as the predicted stall. The parameter Mu is the rotational Mach number (impeller tip speed / inlet total sound speed).
This is an ultra-low flow coefficient industrial compressor stage with a covered simple radial impeller, vaneless diffuser and return channel. All predicted and experimental data are normalized by their design point values. Predicted and experimental stage work input coefficients are shown as well as adiabatic head coefficents at the impeller, diffuser and return channel (stage) exits. The performance of this stage is really dominated by wall friction losses, parasitic losses (windage & disk friction) and substantial cover seal flow leakage as a fraction of the inlet flow.
This is a moderately high flow coefficient air compressor stage designed for a pressure ratio of 3.4. It has a full-inducer impeller with splitter blades, a vaned diffuser and a volute. All predicted and experimental input head (work) and head data are normalized by their design point values. Note that the predicted vaned diffuser stall point is in close agreement with the stage experimental surge flow.
Program CENCOM component performance models (diffusers, return systems and volutes) have also been extensively validated against experimental data obtained from internal traverse data taken during prototype stage performance tests.
Here predicted vaneless diffuser loss coefficients are compared with experimental values for an ultra-low flow coefficient (friction dominated) stage and for a moderately high flow coefficient (diffusion dominated) stage.
Here predicted return system (crossover bend and return channel) loss coefficients are compared with experimental values for a high flow coefficient stage. This is a very severe test due the very wide passages, the 180 degree bend, followed by the return channel vanes and then followed by the 90 degree bend. In addition, the entire stage performance prediction is severely tested to achieve the good estimate of the return system matching to the upstream components (i.e., the estimated stage inlet flow where the return system achieves its minimum loss).